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A discrete model for the efficient analysis of timevarying narrowband communication channels
, 2006
"... We derive an efficient numerical algorithm for the analysis of certain classes of Hilbert–Schmidt operators that naturally occur in models of wireless radio and sonar communications channels. A common shorttime model of these channels writes the channel output as a weighted superposition of time a ..."
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Cited by 3 (1 self)
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We derive an efficient numerical algorithm for the analysis of certain classes of Hilbert–Schmidt operators that naturally occur in models of wireless radio and sonar communications channels. A common shorttime model of these channels writes the channel output as a weighted superposition of time and frequency shifted copies of the transmitted signal, where the weight function is usually called the spreading function of the channel operator. It is often believed that a good channel model must allow for spreading functions containing Dirac delta distributions. However, we show that many narrowband finite lifelength systems such as wireless radio communications can be well modelled by smooth and compactly supported spreading functions. Further, we exploit this fact to derive a fast algorithm for computing the matrix representation of such operators with respect to well timefrequency localized Gabor bases (such as pulseshaped OFDM bases). Hereby we use a
A Generalization of Binomial Queues
 Information Processing Letters
, 1996
"... We give a generalization of binomial queues involving an arbitrary sequence (mk )k=0;1;2;::: of integers greater than one. Different sequences lead to different worst case bounds for the priority queue operations, allowing the user to adapt the data structure to the needs of a specific application. ..."
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Cited by 2 (0 self)
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We give a generalization of binomial queues involving an arbitrary sequence (mk )k=0;1;2;::: of integers greater than one. Different sequences lead to different worst case bounds for the priority queue operations, allowing the user to adapt the data structure to the needs of a specific application. Examples include the first priority queue to combine a sublogarithmic worst case bound for Meld with a sublinear worst case bound for Delete min. Keywords: Data structures; Meldable priority queues. 1 Introduction The binomial queue, introduced in 1978 by Vuillemin [14], is a data structure for meldable priority queues. In meldable priority queues, the basic operations are insertion of a new item into a queue, deletion of the item having minimum key in a queue, and melding of two queues into a single queue. The binomial queue is one of many data structures which support these operations at a worst case cost of O(logn) for a queue of n items. Theoretical [2] and empirical [9] evidence i...
Liv^sic theorems and stable ergodicity for group extensions of hyperbolic systems with discontinuities
, 2002
"... Abstract We prove measurable Liv^sic theorems for Lie group valued cocycles over certain classes of uniformly hyperbolic maps with discontinuities, in particular the fitransformation, C 2 Markov maps and a simple class of toral linked twist maps. As an application we establish stable ergodicity res ..."
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Cited by 1 (1 self)
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Abstract We prove measurable Liv^sic theorems for Lie group valued cocycles over certain classes of uniformly hyperbolic maps with discontinuities, in particular the fitransformation, C 2 Markov maps and a simple class of toral linked twist maps. As an application we establish stable ergodicity results for compact group extensions of certain classes of uniformly hyperbolic systems with discontinuities. Introduction Liv^sic theorems establish that solutions to dynamical cohomological equations which are assumed to have a certain degree of regularity have in fact a greater degree of regularity. For hyperbolic systems the techniques in this area are still mainly based on the seminal ideas of Liv^sic [15, 16]. By measurable Liv^sic theorems we mean theorems that apply to dynamical cohomological equations in which solutions are a priori only measurable. Measurable Liv^sic theorems have applications to the study of ergodicity of compact group extensions of hyperbolic systems, since an obstruction to ergodicity of such systems is given by the existence of group valued measurable solutions to a cohomological equation. Good references on the state of the art for Liv^sic theorems are [8, 17, 23].
Time Varying Narrowband Communications Channels: Analysis and Implementation
, 2007
"... We derive and describe a Matlab implementation of an efficient numerical algorithm for the analysis of certain classes of Hilbert–Schmidt operators that naturally occur in models of wireless radio and sonar communications channels. A common shorttime model of these channels writes the channel outpu ..."
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We derive and describe a Matlab implementation of an efficient numerical algorithm for the analysis of certain classes of Hilbert–Schmidt operators that naturally occur in models of wireless radio and sonar communications channels. A common shorttime model of these channels writes the channel output as a weighted superposition of time and frequency shifted copies of the transmitted signal, where the weight function is often called the spreading function of the channel operator. It is often believed that a good channel model must allow for spreading functions containing Dirac delta distributions. However, we show that many narrowband finite lifelength channels such as wireless radio communications can be well modelled by smooth and compactly supported spreading functions. We derive a fast algorithm for computing the matrix representation of such operators with respect to well timefrequency localized Gabor bases, such as pulse shaped OFDM bases. Hereby we use a minimum of approximations, simplifications, and assumptions on the channel. The primary intended target application
DOI: 10.1080/17459737.2011.608819 ZRelation and Homometry in Musical Distributions
, 2012
"... This is a preprint of an article whose final and definitive form has been published in the Journal of Mathematics and Music (JMM) c ○ 2011 Taylor & Francis. The published article is available online at ..."
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This is a preprint of an article whose final and definitive form has been published in the Journal of Mathematics and Music (JMM) c ○ 2011 Taylor & Francis. The published article is available online at
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"... Fractional differentiation systems are characterized by the presence of nonexponential aperiodic multimodes. Although rational orthogonal bases can be used to model any L2[0, ∞ [ system, they fail to quickly capture the aperiodic multimode behavior with a limited number of terms. Hence, fractional ..."
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Fractional differentiation systems are characterized by the presence of nonexponential aperiodic multimodes. Although rational orthogonal bases can be used to model any L2[0, ∞ [ system, they fail to quickly capture the aperiodic multimode behavior with a limited number of terms. Hence, fractional orthogonal bases are expected to better approximate fractional models with fewer parameters. Intuitive reasoning could lead to simply extending the differentiation order of existing bases from integer to any positive real number. However, classical Laguerre, and by extension Kautz and generalized orthogonal basis functions, are divergent as soon as their differentiation order is noninteger. In this paper, the first fractional orthogonal basis is synthesized, extrapolating the definition of Laguerre functions to any fractional order derivative. Completeness of the new basis is demonstrated. Hence, a new class of fixed denominator models is provided for fractional system approximation and identification.